From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E9B3319617 for ; Thu, 25 Jun 2026 14:02:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782396140; cv=none; b=OJ89rW6YbMr/55ZPMISRNHRxYRkfHcwmeqJlAEtWn7H1NrufF8fMGtLYhmSjSW5RVNyLGyayp72GNw5AvP9p3LjEdpTJGVaxsOZ+TG4NpFNJqRZmSqfFi93JeS2NZCTWzSA2G10chqAzhSXvZQCrQ9yg4Yu9J6iizhy7Jqz4S/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782396140; c=relaxed/simple; bh=6zdmiNOAqKGX+1vgc4hu5H1gHAK96iDAcnyfbkz7XMY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Dgbpr44/2dc3DnXDz8kPlzYIGAMg+0W8szLPBUr8i1KOn5nTJOjPUYZcthhNM4Jii7b+SMRvihI/SxAG9HTdKxQWwhWHaBa+SV385c3hPlsspdBU1L2uOxbEQGstsDd0WVOzbIoMwSYpNffDgJ3za5guNxWkN0QigiSwqJ1ggCc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MlBeAgA4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MlBeAgA4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 588801F000E9; Thu, 25 Jun 2026 14:02:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782396139; bh=6zdmiNOAqKGX+1vgc4hu5H1gHAK96iDAcnyfbkz7XMY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=MlBeAgA48j8VO5jAtfgWxcnZXQvmNu++VkSIk+GO4CuQ3EjcyfQL2cdB/WkkIhEZZ c+YqxP3WVizDttlHHqvUt8x/C+u/3BEe5DQF6KxF+rMmCkKG95Pm8noaiIXa9H0IKO 7mEjaEGdSkKi2Gi93UGMHyqUtGCAMUZLotM2kFxilG0oyj4V9/NpDx0C41YO8vpweB OITbE5pIxQRfYoq2u18S0dalW6Bu6K+Yogy0cDSN1lHIDoZJNNnYaQADav1Ap6LUjd Rw5zapoN+gk1mHokPVxPhJ44Yu92wJ0COCbkYejznwL4wlK8ZJmaS6jabZ6srHfqCb 1aMTJ9/G6C0aw== Date: Thu, 25 Jun 2026 15:02:11 +0100 From: Lorenzo Stoakes To: "David Hildenbrand (Arm)" Cc: Wei Yang , akpm@linux-foundation.org, riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, lance.yang@linux.dev Subject: Re: [PATCH] mm/page_vma_mapped: guard check_pmd() with CONFIG_TRANSPARENT_HUGEPAGE Message-ID: References: <20260624082359.2869-1-richard.weiyang@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Jun 25, 2026 at 03:49:59PM +0200, David Hildenbrand (Arm) wrote: > On 6/25/26 15:45, Lorenzo Stoakes wrote: > > On Wed, Jun 24, 2026 at 08:23:59AM +0000, Wei Yang wrote: > >> The kernel test robot reported a build failure on the parisc architecture > >> when expanding HPAGE_PMD_NR in check_pmd(). > > > > Let me first say that I absolutely hate that we continue to support museum > > piece architectures to the point that we have to make changes in core code > > to accommodate them. > > I wonder why we shouldn't be able to trigger that on other archs with > !CONFIG_TRANSPARENT_HUGEPAGE ? I think this should just use CONFIG_PGTABLE_HAS_HUGE_LEAVES, since that's the property that literally defines whether check_pmd() makes any sense. > > I think the code just relies on pmd_trans_huge() == false, and consequently > check_pmd will get compiled out completely. > > Now, the report was against Wei's new patch. > > There is *nothing* to be fixed for existing code. OK so it's a fix sent in the merge window, against a patch sent in the merge window. Great. I mean, let's all chill here. Sip some wine. Some brandy. Some absinthe. Perhaps even some turpentine* for the connoisseurs! Slow down a bit Wei! You're sending a lot of fiddly series that require a lot of review and we're extremely busy with review already. Please just relax and maybe go water your garden a bit. Have a cornetto :) > > > Fixes: 2aff7a4755be ("mm: Convert page_vma_mapped_walk to work on PFNs") > > is just wrong? Yes therefore it is indeed. Though it's really horrible that we relied on things getting compiled out like that... nasty! > > -- > Cheers, > > David Cheers, Lorenzo *Obligatory safety notice for the overly literal: do not do this, this is a joke.